

def cal_cls_attr(cls_name):
    if 'PyClassA' == cls_name:
        return 'PyClassA_attr'


class PyClassA(object):
    cls_attr1 = cal_cls_attr('PyClassA')


def start():
    print('PyClassA attr:', PyClassA.cls_attr1)
    PyClassA.cls_attr1 = 'PyClassA_attr_mod'
    print('PyClassA attr:', PyClassA.cls_attr1)

